Finding the way to a destination requires knowledge of the surroundings including landmarks, etc., and means for defining a route to the destination.
Blind people or persons with a visual impairment have to find their way to a destination but may not have as much information as a sighted person. The destination is more difficult to identify in open spaces and in new unknown areas. It is also difficult to determine whether or not a user has arrived at the required destination. It may also be necessary to identify the destination. For example if a person is trying to reach one particular room and there is a corridor of several similar rooms one after another (as normally occurs with restrooms), it would be difficult to know which is the right room to enter unless there is a sign (Braille or any other kind) mounted nearby.
Existing solutions are not suitable to solve this problem. Existing systems are able to indicate landmarks that are nearby but fail to determine the orientation (the direction being faced by the user) of the user at a given moment, thus cannot provide accurate directions and guidance to the user. For instance, the Global Positioning System (GPS) is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. GPS technology brings a solution for locating the user but also brings an accuracy error. This is acceptable for other users such as automobiles being routed to a specific destination, where four meters deviation error is not a great concern. Also GPS does not work indoors and in such places accuracy is even more important.
Another solution is a location solution with a triangulation system. The system locates the source location of cellular calls by determining how long it takes a call to reach each of three cell sites, then triangulates the location. Location solutions based on cellular phones and antenna triangulation based on signal strength are also not sufficiently accurate as needed for determining a location and orientation system to work indoors and also suffers from problems of beam reflections on nearby buildings.
These two solutions are suitable to determine the user location but not the user's orientation at a given moment which is a fundamental need for a blind person.
For indoor use there is a partial solution using radio triangulation location. Radio triangulation systems have multiple antennas (acting as either transmitters, receivers or both) placed throughout a building. The signal from a device/user is picked up by multiple receiving antennas. Each of these antennas is in a known location and the distance between the transmitted signal and the received antenna is calculated. The point at which these three radii intersect is the location of the device/user. Location sensing indoor systems using triangulation have the same problem as cellular antenna triangulation of multi-path reflection. This gives a poor accuracy and error which impacts the reliability of the system.
Smart Floor solutions are also used for locating users/people. Footstep profiles of the users are registered in a database. When a user walks on specific load sensitive tiles located in the floor, the system can then recognize and locate the user. The great disadvantage of this solution is that it needs to be set up for each particular user and over the building or space. It is not suitable for the general public and therefore does not provide a solution for public spaces such as buildings.
Infrared Auditory Signage (RIAS) is another solution. This solution operates by the installation of infrared transmitters that diffuse repeated human voice messages regarding the location of the user. The user receives these messages on small, hand held or head mounted receivers. These messages can be transmitted via sound or via infrared light. RIAS systems offer a solution based on a directional beam. This system has the disadvantage of blocking and screening. This type of system is inconvenient because the user needs to be alert in advance of the location of the transmitter in order to align the receiver so the receiver can obtain the information desired.
Present Radio Frequency Identification (RFID) solutions offer relative positioning indications for users but they fail to give information relating to orientation of the user. Solutions such as RFID Grid have the inconvenience that the orientation (direction in which the user is facing) is based on two readings done consecutively after movement of the user, this adds an error factor. Also outdoor orientation is processed by an insert mounted on a housing which could be raised and a groove (or slot) in the shape of a triangle located on the top surface of it. This triangle has to be touched by the user to activate the system and thus advanced knowledge of where to find it is needed.
S. Willis and S. Helal describe a solution for the orientation of users entitled “a passive RFID information grid for location and proximity sensing for the blind user”. The article describes a grid which is located indoors all over the surface of the floor. This grid allows a user to be guided sequentially from one cell to another one until a destination is reached. In this kind of system, each cell contains location information related to a defined place and a precise environment. A disadvantage of such system is that when a furniture is placed on a cell, the orientation of the user is disturbed. A second disadvantage of this system is that this grid can not be reused in another location as all cells are programmed with specific details from a defined space and can not be reprogrammed.